ViewPager动态添加、删除Fragment，且提供红色小圆球指示当前位置

àì夳堔傛蜴生んèń 2023-10-16 20:58 9阅读 0赞

简单的说，代码要实现的是类似于现在通用新闻客户端头部的新闻图片展示。现在的新闻客户端顶部一般放有图片展示区，假设有5张图片，用户可以左右侧滑翻阅，同时提供一行5个红色小圆球（红色小圆球的个数等于图片数目），假设当用户翻到第3张图片时候，红色小圆球也相应的指示到第3位置。自然，图片标题也要设置成相对应于图片的内容。

代码功能简要说明：

（1）一个ViewPager，每个page加载不同的Fragment，整个ViewPager中的Fragment可以动态删除和添加。

（2）当ViewPager在左右侧滑时候，下方的提示和红色小圆球也相应的滑动指示当前的Page在所有Page中位置和标题。

MainActivity.java

import android.os.Bundle;
    import android.support.v4.app.Fragment;
    import android.support.v4.app.FragmentActivity;
    import android.support.v4.app.FragmentTransaction;
    
    public class MainActivity extends FragmentActivity {
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            
      
            Fragment newFragment =new  ViewPagerWithCircleIndicatorView();
            FragmentTransaction transaction =getSupportFragmentManager().beginTransaction();
            transaction.replace(R.id.fragment,newFragment);
            transaction.commit();
    
        }
    }

MainActivity.java需要的activity\_main.xml

ViewPagerWithCircleIndicatorView.java 该类是重点。实现ViewPager和红色小圆球指示器。

import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.Random;
    
    import zhangphil.libs.view.CircleIndicatorView;
    
    import com.example.viewpager_fragment.R;
    
    import android.graphics.Color;
    import android.os.Bundle;
    import android.os.Handler;
    import android.os.Message;
    import android.support.v4.app.Fragment;
    import android.support.v4.app.FragmentManager;
    import android.support.v4.app.FragmentPagerAdapter;
    import android.support.v4.app.FragmentStatePagerAdapter;
    import android.support.v4.view.ViewPager;
    import android.view.LayoutInflater;
    import android.view.Menu;
    import android.view.MenuInflater;
    import android.view.MenuItem;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.TextView;
    
    /**
     * @author Phil
     *
     */
    public class ViewPagerWithCircleIndicatorView extends Fragment {
    
    	private MyFragmentPagerAdapter mPagerAdapter;
    	private ViewPager mViewPager;
    
    	private Handler handler;
    	private final int MESSAGE_WHAT_CHANGED = 100;
    
    	private ArrayList<HashMap<String, Object>> mArrayList = null;
    	private final String FRAGMENT = "fragment_tag";
    
    	@Override
    	public void onCreate(Bundle savedInstanceState) {
    		super.onCreate(savedInstanceState);
    		setHasOptionsMenu(true);
    		mArrayList = new ArrayList<HashMap<String, Object>>();
    	}
    
    	@Override
    	public View onCreateView(LayoutInflater inflater, ViewGroup container,
    			Bundle savedInstanceState) {
    		View mView = inflater.inflate(R.layout.viewpager_fragment, null);
    
    		mViewPager = (ViewPager) mView.findViewById(R.id.viewpager);
    
    		mPagerAdapter = new MyFragmentPagerAdapter(getFragmentManager());
    		mViewPager.setAdapter(mPagerAdapter);
    		mViewPager
    				.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
    
    					@Override
    					public void onPageSelected(int pos) {
    						set(pos);
    					}
    
    					@Override
    					public void onPageScrolled(int arg0, float arg1, int arg2) {
    
    					}
    
    					@Override
    					public void onPageScrollStateChanged(int arg0) {
    
    					}
    				});
    
    		final TextView circleIndicatorView_TextView=(TextView)mView.findViewById(R.id.circleIndicatorView_TextView);
    		final CircleIndicatorView mCircleIndicatorView = (CircleIndicatorView) mView
    				.findViewById(R.id.circleIndicatorView);
    		handler = new Handler() {
    			public void handleMessage(Message msg) {
    				super.handleMessage(msg);
    				switch (msg.what) {
    				case MESSAGE_WHAT_CHANGED:
    					mCircleIndicatorView.setCircleCount(mPagerAdapter
    							.getCount());
    					mCircleIndicatorView.setCircleSelectedPosition(mViewPager
    							.getCurrentItem());
    					mCircleIndicatorView.setSelectedCircleRadius(7);
    					mCircleIndicatorView.setCircleUnSelectedColor(Color.BLUE);
    					mCircleIndicatorView.drawCircleView();
    					
    					TestFragment tf=(TestFragment) mArrayList.get(mViewPager.getCurrentItem()).get(FRAGMENT);
    					String title=tf.getTitle();					
    					circleIndicatorView_TextView.setText(title);
    					
    					break;
    				}
    			};
    		};
    
    		
    	
    		// 初始化，在此，可选
    		initialization();
    
    		// 初始化选择第一项
    		if (mPagerAdapter.getCount() > 0) {
    			set(0);
    		}
    
    		return mView;
    	}
    
    	private void initialization() {
    		// 在这里做初始化工作，如果有指定的Fragment，在此预装载
    
    		// Fragment fragment;//创建一个Fragment
    		// View view;//一个下方选项卡的View
    		// add(fragment, view);
    	}
    
    	private void add(Fragment fragment) {
    
    		HashMap<String, Object> map = new HashMap<String, Object>();
    
    		Bundle args = new Bundle();
    		fragment.setArguments(args);
    		map.put(FRAGMENT, fragment);
    		
    		mArrayList.add(map);
    	}
    
    
    	private final void delete(int pos) {
    		mArrayList.remove(pos);
    		mPagerAdapter.notifyDataSetChanged();
    	}
    
    	private void set(int pos) {
    		mViewPager.setCurrentItem(pos, true);
    		handler.sendEmptyMessage(MESSAGE_WHAT_CHANGED);
    	}
    
    	private class MyFragmentPagerAdapter extends FragmentStatePagerAdapter {
    
    		public MyFragmentPagerAdapter(FragmentManager fm) {
    			super(fm);
    		}
    
    		@Override
    		public Fragment getItem(int pos) {
    			return (Fragment) mArrayList.get(pos).get(FRAGMENT);
    		}
    
    		@Override
    		public int getItemPosition(Object object) {
    			return FragmentPagerAdapter.POSITION_NONE;
    		}
    
    		@Override
    		public int getCount() {
    			return mArrayList.size();
    		}
    
    		@Override
    		public void notifyDataSetChanged() {
    			super.notifyDataSetChanged();
    			handler.sendEmptyMessage(MESSAGE_WHAT_CHANGED);
    		}
    
    	}
    
    	private Fragment loadFragment() {
    		return new TestFragment();
    	}
    
    	protected void onActionAdd() {
    		add(loadFragment());
    		mPagerAdapter.notifyDataSetChanged();
    	}
    
    	@Override
    	public boolean onOptionsItemSelected(MenuItem item) {
    
    		switch (item.getItemId()) {
    		case R.id.action_add:
    			onActionAdd();
    			break;
    
    		case R.id.action_dele:
    			delete(mViewPager.getCurrentItem());
    			set(mViewPager.getCurrentItem());
    			break;
    
    		default:
    			break;
    		}
    
    		return super.onOptionsItemSelected(item);
    	}
    
    	@Override
    	public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
    		inflater.inflate(R.menu.main, menu);
    	}
    	
    
    	//
    	// 仅仅用于测试的Fragment，在ViewPager中加载
    	//
    	public static class TestFragment extends Fragment {
    
    		private final	String title = new Random().nextInt(20)+"";
    
    		@Override
    		public View onCreateView(LayoutInflater inflater, ViewGroup container,
    				Bundle savedInstanceState) {
    
    			TextView tv = new TextView(getActivity());
    
    			String str = "Fragment : "+title+"\n";
    			for (int i = 0; i < 500; i++)
    				str = str + i + "--";
    
    			tv.setTextColor(Color.LTGRAY);
    			tv.setText(str);
    
    			return tv;
    		}
    		
    		public	String	getTitle(){
    			return	title;
    		}
    	}
    }

红色小圆球的绘制类：CircleIndicatorView.java

import android.content.Context;
    import android.graphics.Canvas;
    import android.graphics.Color;
    import android.graphics.Paint;
    import android.util.AttributeSet;
    import android.view.View;
    
    public class CircleIndicatorView extends View { 
    	
        public CircleIndicatorView(Context context, AttributeSet attrs){   
        	       super(context, attrs);  
        }
        
        private	int	gap=20;//各个横向排列的小球间距
    	public	void	setCirlceGap(int gap){
    	    	this.gap=padding;
    	}
    	public	int	getCirlceGap(){
    	    	return	gap;
    	}
        
        private	int	padding=20;
        public	void	setPadding(int padding){
        	this.padding=padding;
        }
        public	int	getPadding(){
        	return	padding;
        }
        
        private	int	circle_normal_radius=5; //普通小球半径
        public	void	setNormalCircleRadius(int radius){
        	this.circle_normal_radius=radius;
        }
        public	int	getNormalCircleRadius(){
        	return	circle_normal_radius;
        }
        
        private	int	circle_selected_radius=5; //被选择的小球半径
        public	void setSelectedCircleRadius(int radius){
        	this.circle_selected_radius=radius;
        } 
        public	int	getSelectedCircleRadius(){
        	return	circle_selected_radius;
        }
        
        private	int	count=0;
        public	void	setCircleCount(int count){
        	this.count=count;
        }
        public	int	getCircleCount(){
        	return	count;
        }
    
        private	int	pos=0;
        public	void	setCircleSelectedPosition(int pos){
        	this.pos=pos;
        }
        public	int	getCircleSelectedPosition(){
        	return	pos;
        }
        
        public	void	drawCircleView(){
        	this.invalidate();
        }
        
        private	int	circleSelectedColor=Color.RED;
        public	void	setCircleSelectedColor(int color){
        	circleSelectedColor=color;
        }
        public	int	getCircleSelectedColor(){
        	return	circleSelectedColor;
        }
        
        private	int	circleUnSelectedColor=Color.LTGRAY;
        public	void	setCircleUnSelectedColor(int color){
        	circleUnSelectedColor=color;
        }
        public	int	getCircleUnSelectedColor(){
        	return	circleUnSelectedColor;
        }
    
        
        @Override  
        protected void onDraw(Canvas canvas) {  
            super.onDraw(canvas); 
            
            Paint p = new Paint();  
            p.setAntiAlias(true);
            
            int w=this.getWidth();
            int h=this.getHeight();
            
            //因为是自右往左绘制小圆圈，需要转化pos的位置。
          int translate_pos=getCircleCount()-getCircleSelectedPosition()-1;
           
          //如果居中绘制则使用start_x，但需要依次递加x坐标轴位置值。
          //int start_x=(w-(CIRCLE_GAP*(getCircleCount()-1)))/2;
            
            for(int i=0;i<getCircleCount();i++){
            	int r=getNormalCircleRadius();
            	
            	if(i==translate_pos){
            		r=getSelectedCircleRadius();
            		p.setColor(getCircleSelectedColor());
            	}
            	else{
            		r=getNormalCircleRadius();
            		p.setColor(getCircleUnSelectedColor()); 
            	}
            	
            	//自右向左绘制。从最右边往左边绘制小球
            	//如果从该自定制的View左边绘制，直接将 x=0即可。
            	canvas.drawCircle(w-i*getCirlceGap()-getPadding(), h/2, r, p);
            }
        } 
    }

ViewPagerWithCircleIndicatorView.java需要的viewpager\_fragment.xml

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        >
        
        
       <FrameLayout 
        android:layout_weight="1"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >
    
        <android.support.v4.view.ViewPager
            android:id="@+id/viewpager"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />
    
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="30dip"
            android:orientation="horizontal"
            android:layout_gravity="bottom" >
    
            <TextView
                android:id="@+id/circleIndicatorView_TextView"
                android:layout_width="0dip"
                android:layout_height="match_parent"
                android:gravity="left"
                android:textColor="#FF0000"
                android:layout_weight="0.618"
                android:singleLine="true"
                android:text="abcdefghijklmnopqrstuvwxyz01234567890123456789" />
            
            <zhangphil.libs.view.CircleIndicatorView
                android:id="@+id/circleIndicatorView"
                android:layout_width="0dip"
                android:layout_height="match_parent"
                android:layout_weight="0.382"/>
            
        </LinearLayout>
    
    </FrameLayout>
     
    </LinearLayout>

系统的添加、删除菜单需要。res\\menu目录下，main.xml，菜单布局文件：

效果图：

![20150209153439054][]

[20150209153439054]: https://img-blog.csdn.net/20150209153439054